Positron-lifetime spectroscopy has been performed in concert with photoluminescence to investigate vacancy-related point defects in polycrystalline diamond films grown by chemical vapor deposition (CVD). Undoped films extensively contain vacancies including monovacancies, divacancies, and vacancy clusters. They are distributed inhomogeneously throughout the films with some crystallites nearly free of vacancies while others contain high concentrations (\ensuremath{\gtrsim} 50 ppm). However, boron doping can dramatically reduce the vacancy content in diamond films. The vacancy-related defects are stable up to 1100 \ifmmode^\circ\else\textdegree\fi{}C. The different luminescence peaks can be related to various types of vacancies present in CVD diamond. \textcopyright{} 1996 The American Physical Society.